If you're looking for a meeting place or a good stop around ½ or halfway between San Luis Obispo and Cambria Pines, you can try Cayucos, CA, which is about half an hour northwest of San Luis Obispo, or about half an hour southeast of Cambria Pines.
About ⅓ or a third of the way, you can stop at Morro Bay, CA. This is about 13 minutes northwest of San Luis Obispo.
About ¾ or three fourths of the way, you can stop at Harmony, CA. This is about half an hour northwest of San Luis Obispo, or about 10 minutes southeast of Cambria Pines.
If you drive straight through without stopping at all, the total distance is 35 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 43 minutes.